Britain Set to Approve Technique to Create Babies From 3 People

LONDON — Despite warnings that a new ethical threshold was being crossed, British lawmakers on Tuesday voted to allow the in vitro creation of babies using the DNA of three people, a procedure that could prevent the inheritance of genetic diseases.

The move would make Britain the first country to authorize an in vitro fertilization technique that involves altering a human egg or embryo before transferring it to the womb.

The issue provoked fierce debate, with some opponents likening the procedure to genetic modification and arguing that it would open the way to the creation of so-called designer babies.

Lawmakers in the House of Commons voted 382 to 128 in favor of the move, which still requires final approval from the House of Lords, the unelected upper chamber of Parliament. The House of Lords rarely rejects the decisions of its elected colleagues.

The vote came after a number of objections were raised, including the fact that other nations, including the United States, have not taken such a step.

Describing the move as “bold” but “considered and informed,” the health minister, Jane Ellison, argued in favor of legalizing the procedure, which is designed to help women with mitochondrial diseases. Defects in the mitochondria — energy-producing structures outside a cell’s nucleus — can result in a range of complications, including muscular dystrophy and heart, kidney and liver failure.

An opponent of the change, Edward Leigh, a Conservative lawmaker and former minister, said before the vote that it was a “monumental decision.”

“If we believe that, sadly, given the nature of the human condition, there are these appalling diseases, where do we stop?” he asked, calling for full clinical trials to determine the procedure’s safety and effectiveness.

“We will be the first state to authorize this in the world,” Mr. Leigh added. “We will be in a unique position, and we should ask ourselves why no other state — not the European Union, not the U.S., yet — thinks this process is absolutely safe.”

If it wins final approval, as seems likely, the technique is expected to be used only sparingly, and in the cases of women who have faulty mitochondria. The resulting embryo would have nucleus DNA from the child’s parents but mitochondrial DNA from a donor.

Scientists say that the child would inherit the characteristics of the parent, other than the mitochondrial defect, rather than those of the donor.

They also say that the procedure is different from the one used to genetically modify foods, in which individual genes are usually selected to be transferred from one organism into another.

Tuesday’s vote was welcomed by Robert Meadowcroft, chief executive of the Muscular Dystrophy Campaign, who described it in a statement as a “milestone in giving women an invaluable choice, the choice to become a mother without fear of passing on a lifetime under the shadow of mitochondrial disease to their child.”

“There are currently no means to treat devastating mitochondrial diseases, which can cause muscle wastage, loss of vision, stroke-like episodes and a premature death,” the statement added. “Preventing inheritance, where possible, remains our only option, and that is why we have invested in and wholly support this pioneering technique.”

Some groups opposed to the procedure, including Human Genetics Alert, had likened it to genetic modification. “Although food crops, bacteria and animals have been genetically engineered for the last 20 years, there has been a worldwide consensus, embodied in legislation in over 60 countries, that we should not attempt to do the same with human beings,” the group said on its website.

“This is because crossing this line would lead inevitably to a future of ‘designer babies’ and a new consumer-driven eugenics,” the group said.

The Catholic Church in England and Wales said in a statement that it seemed “extraordinary that a license should be sought for a radical new technique affecting future generations without first conducting a clinical trial.”

“There are also serious ethical objections to this procedure, which involves the destruction of human embryos as part of the process,” Bishop John Sherrington said in the statement.

The Church of England argued that there should be “more time for consultation and research,” while adding that the church did not want to prevent people “from benefiting from a major advance in genetics and assisted reproduction.”

A version of this article appears in print on , Section A, Page 4 of the New York edition with the headline: Britain Set to Approve Technique to Create Babies From 3 People. Order Reprints | Today’s Paper | Subscribe